split rim
A wheelrim consisting of several connected pieces, generally used on large and heavy vehicles.
split rim: a wheel rim made in separable pieces
A split rim is a wheel rim manufactured in two or more segments that bolt together around a common center. Unlike a one-piece rim, the segments can be disassembled, allowing tire technicians to remove and reinstall tires without dismounting the entire wheel from the vehicle. The rim segments are held together by cap screws, usually located on the inner edge facing the wheel center.
Split rims are standard on heavy trucks, trailers, and buses where tire changes happen frequently and removing the entire wheel is impractical. A typical split rim for a truck might consist of a side ring, a base ring, and a locking ring. The base ring forms the structural foundation; the side ring provides the outer edge; the locking ring secures the tire bead and keeps the assembly from separating under load. The segments are typically forged steel or ductile iron, sized for loads between 10,000 and 50,000 pounds per wheel depending on application.
Maintenance and hazards
Split rims require more careful maintenance than one-piece wheels. The bolted joints must be torqued to manufacturer specification, typically between 300 and 500 foot-pounds for truck applications. Bolts work loose from vibration and require regular inspection. A rim with loose segments can shed pieces at highway speed, creating a serious hazard. Corrosion where segments meet can seize bolts and make disassembly difficult. Technicians must inspect the mating surfaces for rust pitting or dirt before reassembly.
The design gained popularity because tire repair and replacement on large vehicles became faster and safer without manhandling entire wheels. However, split rims have fallen out of favor in some markets since the 1990s due to improved one-piece rim technology and the safety record of poorly maintained split rim assemblies. Modern regulations in some countries now restrict their use on certain vehicle classes. Cost remains the main reason they persist on commercial fleets: the initial purchase price is lower, and damaged segments can sometimes be replaced individually rather than scrapping an entire wheel.